Final answer:
A TLD (Top-Level Domain) is a three-letter extension in a web address that identifies the type of organization associated with the website.
Step-by-step explanation:
A TLD (Top-Level Domain) is a three-letter extension in a web address which identifies the type of organization associated with the website. It is the last part of a domain name, following the dot (.) symbol. For example, in the URL 'www.example.com', the '.com' is the TLD, indicating that the website is associated with a commercial or business organization.